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The constantly increasing growth of the space debris population is also causing that more and more devices are looking into the sky in search of undetected objects. The process of orbit determination and further object cataloguing requires the initialisation of the object orbital state. This process is particularly complex in the cases when only angular observations from passive devices are available (e.g. topocentric right ascension and declination from a ground telescope). This paper describes the process of initial orbit determination when only a limited number of angular observations are available. Different orbital scenarios (e.g. LEO, MEO, GEO) are analysed together with the available algorithms. The analysis focuses on the suitability of the algorithm for the different orbital regimes and also in the robustness of the solution. The main objective of the analysis is to evaluate the adaptation of the algorithms and their parameterisation for the implementation in operational automated scenarios.

Coastal areas are vulnerable ecosystems comprising unique biological niches that require protection. Identification of relevant types of hazards at the appropriate temporal and spatial scale is crucial to detect their sources and origin, to understand the processes governing their magnitude and distribution, and to ultimately evaluate and manage their risks and consequences preventing economic losses. SCHeMA aims to provide an open and modular sensing solution for autonomous in situ high resolution mapping of a range of anthropogenic and natural chemical compounds coupled to master bio-physicochemical parameters. User-friendly data discovery, access and download as well as interoperability with other projects will be achieved via dedicated interface compatible with INSPIRE and GEO/GEOSS standards and principles.

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<p>The European Copernicus Sentinel-3 mission, a jointly operated mission by ESA and EUMETSAT, consists of two satellites equipped with GPS and DORIS receivers, and a Laser Retro Reflector (LRR) array, which allows tracking the satellites by Satellite Laser Ranging (SLR). The SLR observations are mainly used for the validation of GPS- and/or DORIS-derived precise orbit solutions. The SLR residuals are derived from the simple difference between observed and computed range between SLR station and the satellite. Only a subset of the SLR stations tracking the satellites is normally used for this purpose. The subset consists of stations delivering good quality observations on a long-term. The station selection is regularly reviewed to guarantee a continuous quality for the orbit validation.</p><p>Instead of using only a subset of the stations it would be preferable to use as many laser tracking data as possible. Long-term and highly accurate orbit time series of low Earth orbiting satellites can be used to estimate station range biases. The SLR validation is significantly improved by adding these station range biases due to additional stations and due to the removal of SLR related systematic patterns.</p><p>In the Copernicus POD Service (CPOD), the SLR station range biases are estimated based on a combined Sentinel-3A and -3B orbits computed from different orbit providers (the CPOD Quality Working Group). Performance, quality, mission dependency and stability of these SLR station range biases are analysed based on operational CPOD orbits and orbit solutions delivered by the Copernicus POD Quality Working Group.</p>